1. Field of the Invention
The present invention relates to a draining device for a starter, which is used to drain the water which has invaded in the starter.
2. Discussion of Background
FIG. 4 is an axial sectional view showing the entire structure of a starter having a starter draining device. In FIG. 4, reference numeral 1 designates an electric motor armature. Reference numeral 2 designates a yoke constituting a casing for the starter, and on the inner circumferential surface of which field coils 3 are arranged. With the rear end of the yoke 2 is engaged a rear bracket (rear part of the casing) 4, which has its rear end provided with a bearing 5. The rotary shaft 6 of the armature is supported at its rear end by the bearing 5. To the rear bracket 4 is fixed a brush device 8 which is in sliding contact with the commutator 7 of the armature 1. At the front side of the armature 1 a pinion 10 is arranged through an overrunning clutch 9. The pinion 10 and the overrunning clutch 9 are carried on the armature rotary shaft 6 so as to be movable in the axial direction. Reference numeral 11 designates a front bracket (front part of the casing) which is engaged with the front end of the yoke 2. The armature rotary shaft 6 is supported at its front end by the front bracket 11 through a bearing 12. To the front bracket 11 is integrally fixed a solenoid switch device 13, having a casing 14. Lever 15 has one end engaged with a plunger 16 of the solenoid switch device 13, and its other end engaged with the rear end of the overrunning clutch 9, and which is arranged so as to be swingable about its fulcrum.
Reference numeral 17 designates a tubular draining member which is engaged with a lower portion of the rear bracket 4 and is made of rubber, and which has the structure shown in FIG. 5. Specifically, the draining member 17 is integrally provided with an engaging portion 17a and a tubular body 17b, the draining member being engaged with the rear bracket at the engaging portion. The tubular body 17b has on its inner circumferential surface a plurality of lips 17c which are directed toward the leading end of the tubular body or the direction perpendicular to the inner circumferential surface, facing each other. Such lips are alternately formed to define a baffle labyrinth structure.
In the starter constructued in this way, the solenoid switch device 13 is actuated to let the armature 1 rotate and the pinion 10 move in the forward direction. As a result, the pinion is brought into mesh with a ring gear to start the engine. Because such operation is well known, detailed description on it is omitted.
In the draining device of the conventional starter, the draining member 17 drains the water which has invaded the inside of the starter, and also prevents water splashed from below from coming into the inside of the starter by virture of the tubular structure and the labyrinth structure in the tubular body.
However, when a high water pressure is applied to the draining member 17 as in the case of, e.g. water splashed by a wheel, or water sprayed by a high pressure car wash device, the water invades the inside of the starter from the leading end of the draining member 17 in some cases. Such cases create a problem wherein the brush device 8 rusts away to prevent the motor from functioning properly.
In order to solve such problem, it could be thought out that the length of the tubular body 17b is sufficiently extended to prevent the water from invading the inside of the starter. Such solution is difficult to be adopted because the space for mountaining the starter to a vehicle is, in general, limited, which means that the length of the draining member 17 is also limited.